Key dates between the murder of the teenager in April 1993 and the conviction of Gary Dobson and David Norris in 2012

22 April Stephen Lawrence is stabbed to death in an unprovoked attack by a gang of white youths as he waits at a bus stop in Eltham, south-east London, with his friend Duwayne Brooks.

26 April Four prime suspects put under surveillance.

4 May Lawrence family complains that police are not doing enough to catch Stephen's killers.

7 May Homes of brothers Neil and Jamie Acourt, and David Norris and Gary Dobson searched. Acourt brothers and Dobson are arrested, then released on bail. Norris surrenders to police three days later.

13 May Identification parades done for Neil Acourt, Dobson and Norris. Neil Acourt is identified by Brooks as one of the gang responsible. Acourt is charged with the murder of Lawrence and the attempted murder of Stacey Benefield a month earlier. Norris is charged with the attempted murder of Benefield.

18 June Funeral of Stephen Lawrence.

23 June Luke Knight is charged with Lawrence's murder and remanded in custody.

29 July Committal proceedings scheduled for Neil Acourt and Knight, but the Crown Prosecution Service formally discontinues the prosecution after a meeting between the CPS and the senior investigating officer.

August Review set up by Scotland Yard.

22 December Southwark coroner Sir Montague Levine halts an inquest into Lawrence's death after the family's barrister, Michael Mansfield QC, says there is "dramatic" new evidence.

16 April CPS says the new evidence is insufficient to support murder charges.

September Lawrence family begins a private prosecution against the prime suspects.

18 April Murder trial begins against Neil Acourt, Knight and Dobson at the Old Bailey.

25 April Case collapses after Mr Justice Curtis rules that identification evidence from Duwayne Brooks is inadmissible. All three are acquitted.

13 February Inquest into Lawrence's death ends with a verdict from the jury that he was "unlawfully killed by five white youths".

Lawrence's parents make a formal complaint against MPS.

March Kent police inquiry on behalf of Police Complaints Authority.

31 July Judicial inquiry of the case is announced by the new home secretary, Jack Straw.

15 December Police Complaints Authority report on the original police investigation of Lawrence's murder identifies "significant weaknesses, omissions and lost opportunities". The report found no evidence to support the allegation of racist conduct by any MPS officer involved in investigation.

16 March Public inquiry under Lord Macpherson begins.

17 June Metropolitan police make a formal apology to the Lawrence family.

30 June When Dobson, Norris, Knight, Neil Acourt and Jamie Acourt attend the inquiry, protesters shout abuse and pelt them with eggs.

24 February Report into the case and its wider implications by Macpherson concludes the police investigation was "marred by a combination of professional incompetence, institutional racism and a failure of leadership by senior officers". The charge of institutional racism in particular prompts a series of changes within the Metropolitan police.

March 1999 -2003 Deputy assistant commissioner John Grieve begins a third major investigation, Operation Athena Tower.

5 May CPS announces there is insufficient evidence to prosecute anyone for Lawrence's murder.

April Government scraps the double jeopardy legal principle, which prevented suspects being tried twice for the same crime.

July BBC documentary alleges police corruption in the Lawrence case. It is suggested that Clifford Norris, the gangland father of one of the prime suspects, might have paid the former detective sergeant John Davidson to be kept one step ahead of the investigation.

9 August In the case of Damilola Taylor, the killers are convicted after forensic review of the evidence found spots of blood.

Acting deputy commissioner Cressida Dick decides to mount full cold-case forensic review of exhibits in the Lawrence case.

14 October Independent Police Complaints Commission finds no evidence of police corruption and no evidence of dishonest links between Davidson and Clifford Norris.

8 November Police confirm they are investigating new forensic evidence in the case.

7 February Doreen Lawrence opens a ?10m architecture centre in honour of her son. Two weeks later, vandals smash its windows in a suspected racially motivated attack.

22 April Memorial service on 15th anniversary of Lawrence's death. Police told by scientists they have found a spot of blood on the collar of Dobson's jacket.

7 September Dobson and Norris arrested.

8 September Dobson and Norris charged with the murder

18 May Court of appeal quashes Dobson's acquittal, paving the way for trial to go ahead.

14 November Dobson and Norris face trial.

3 January Gary Dobson, 36, and David Norris, 35, are found guilty of murder by a jury at the Old Bailey.

Today They will be sentenced.